President Donald Trump’s decision to withdraw from the Paris climate agreement is the biggest failure of leadership in American history. But there are Republicans in Congress who previously demonstrated their willingness to lead on climate change, and the moment has arrived for them to step up again.

Last month, three GOP senators committed an act of political courage by putting environmental stewardship above partisan politics.

In the waning days of the Obama administration, the president’s team issued a rule to limit the amount of methane released during oil and gas operations on federal land. Methane is a greenhouse gas with heat-trapping properties at least 30 times more powerful than carbon dioxide, and so the rule had the effect of mitigating climate change.

The House of Representatives had already repealed the methane rule. Swift repeal was anticipated in the Senate. What was not anticipated was the integrity of three senators who had previously taken action in the hope of preserving a stable climate.

Lindsey Graham of South Carolina, Susan Collins of Maine, and John McCain of Arizona cast the deciding votes that prevented the repeal measure from moving forward. The turn of events caught both industry and environmental advocates by surprise, but this is not the first time these Republicans have stepped up where climate change is concerned.

In 2009, Graham committed what many believed was political suicide when he collaborated with then-senators John Kerry and Joe Lieberman to draft a Senate version of the cap-and-trade bill that had narrowly passed the House. He came under relentless attack back home in South Carolina and spent the next four years beating back challengers to retain his seat.

Collins worked with Washington state Democrat Maria Cantwell to introduce the Carbon Limits and Energy for American Renewal (CLEAR) Act in December of 2009. The CLEAR Act was a simplified version of cap-and-trade with most of the revenue returned to households, an approach that came to be known as cap-and-dividend. Like the Kerry-Lieberman bill, the CLEAR Act languished and died in the 111th Congress. Despite her leadership with the CLEAR Act, Collins received little acknowledgment or appreciation back home and has since refrained from any major initiatives on climate change.

And McCain? He teamed up with Lieberman to introduce the Climate Stewardship Act in 2003, but his bill was defeated 55-43. Undaunted, he tweaked the bill and reintroduced it in 2005, though it fared no better. Any other politician would have cut his losses at this point, but McCain tried once more in 2007. It never got to the floor. Since then, McCain, like Graham and Collins, hasn’t touched any significant legislation to deal with carbon emissions.

But with their vote to block repeal of the methane rule, Graham, Collins and McCain have stirred the embers of their once-burning passion to preserve a world that is hospitable to future generations. That is the legacy these three hoped to achieve years ago, a legacy that is still within their reach.

Support is growing within conservative circles for a simple, market-based approach to reducing carbon pollution, one that would make regulatory solutions unnecessary.

It’s called carbon fee and dividend, and it works like this:

Apply a fee to fuels based on the amount of carbon dioxide they will emit when burned. Increase the fee over time, thereby creating the price signal to transition to cleaner sources and uses of energy and to increase energy efficiency. To shield families from the economic impact of rising energy costs, return all the revenue from the carbon fee to every household as equal shares. To maintain a level playing field for American businesses — and to encourage other nations to follow our lead — apply an adjustment fee on imports coming from nations that do not have an equivalent carbon price.

Earlier this year, such a policy was proposed by a group of conservatives under the Climate Leadership Council. The authors included two former secretaries of state, George Shultz and James Baker, as well as former Treasury Secretary Hank Paulson, pretty good company for any Republican.

Graham, Collins, and McCain were once champions on climate change. With Trump’s announcement to withdraw from the Paris accord, it’s time for them to reassert their leadership on this issue by introducing and fighting for a revenue-neutral fee on carbon. They were ahead of their time years ago, but it appears their time has come.

Mark Reynolds is executive director of Citizens’ Climate Lobby, a non-partisan advocacy organization working to preserve a stable climate.